Fuse device



Jan. 27, 1959 L. v. CHABALA ETAL FUSE DEVICE Filed Feb. 26. 1954 Fig.l.

S R o T N E V N Leonard V. Chobolo 8| George A. Rus'nok.

ATTORN FUSE DEVICE Leonard V. Chabala, Pittsburgh, and George A. Rusnak,

Whitaker, Pa, assignors to Westinghouse Electric Corporation, lEast Pittsburgh, Pih, a corporation of lennsylvania Application February 26, 1954, Serial No. 412,734

7 Claims. (Cl. 200-113) This invention relates to fuse devices in general, and, more particularly, to fuse devices for protecting capacitors, transformers, or similar equipment when connected to an energized line.

It is a general object of our invention to provide a fusible device which is economical to manufacture, composed of a few, simple parts, and which will provide effective operation while in service.

A more specific object of our invention is to provide an improved fusible device which may be mounted upon the terminal of a capacitor, transformer, or similar equipment, and which, when blown, will cause a removal of the fuse housing and energized lead away from the terminal of such equipment so that a separation gap in free air is provided between the detached energized lead and the fuse base which remains secured to the terminal of such electrical equipment. This has the distinct advantage that charring of the fuse tube will not cause areover, and, in addition, a ready indication of fuse operation is thereby obtained.

Still another object of our invention is to provide an improved fuse device in which the fuse link is so formed as to provide a locking arrangement for fixedly securing the fuse tube, or fuse housing, in position.

Yet a further object is to provide an improved fuse device in which the fuse link locks the fuse tube in position, and yet the energized lead is secured to the fuse link in such a position so that upon fusing of the fuse link, the fuse tube will become detached from the base and remain with the energized lead, covering the exposed end of the same, and, in addition, providing an adequate gap in free air between the base and the detached energized lead.

An additional object of our invention is to provide an improved locking arrangement for the fuse tube or housing of a fusible device by preforming the fuse link.

Although our invention has particular applicability to secondary capacitor fuses, in that individual fuses may be supplied for 230 volt capacitors to prevent case rupture if capacitor short-circuits occur, nevertheless, it will be obvious to those skilled in the art that certain features of our invention may be applied to other apparatus than secondary capacitors, such as transformers or similar devices which it is desired to electrically protect when connected to an energized line. Our invention has distinct pertinence to such applications where, in addition, it is desired to cause a physical removal, or separation, of the energized lead away from the terminal of such an electrical devi e and to cover the exposed end of the energized lead to prevent a lineman from contacting the energized lead and possibly being injured by such contact.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

Figure 1 illustrates a side elevational view, partially in vertical section, of an application of our fuse device to a secondary capacitor, the dotted lines indicating the States atent F 2,871,313 Patented Jan. 27, 1959 position of the energized lead following blowing of the use;

Fig. 2 is an enlarged sectional view with respect to Fig. 1 through the fuse tube at the edge of the link after the blowing operation has taken place, and the fuse device is dangling from theenergized line in the manner as indicated by the dotted lines in Fig. 1;

Fig. 3 is a side elevational view of our improved fuse device before attachment to the terminal of a capacitor, transformer or similar device;

Fig. 4 is a horizontal sectional view taken through the improved device substantially on the line IV-'IV of Fig. 3;

Fig. 5 is a vertical sectional view taken through the fuse device of Fig. 3;

Fig. 6 is an enlarged side elevational view of the improved fuse link utilized in the fuse device;

Fig. 7 is an enlarged side elevatioual view of the mounting base of the fuse device;

Fig. 8 is a top plan view of the fuse mounting base illustrated inFig. 7; and,

Fig. 9 is an enlarged sectional view taken substantial- 1y along the line IX-IX of Fig. 5.

Referring to the accompanying drawing, and more particularly to Fig. 1 thereof, the reference numeral 1 indicates an energized line. A clamp 2 is secured to the line 1 and has connected thereto a flexible energized lead 3, which preferably is covered with insulation 4, as indicated in Fig. 2. The energized lead 3 connects, in this particular instance, a capacitor 5 into the circuit, for purposes of power-factor correction, or for other advantageous functions, as well known by those skilled in the art.

instead of employing a capacitor 5, a transformer or similar device, which it is desired to electrically protect, could be employed. Merely for purposes of illustration is the capacitor 5 illustrated in Fig. 1.

As shown, the capacitor 5 has two terminal studs 6, 7. The terminal stud 6 is electrically connected by a lead 8 to ground, as shown, whereas the terminal stud 7 has a fuse device 9 associated therewith to electrically protect the capacitor 5 should a short-circuit occur interiorly thereof. The fusible device 9 not only protects the capacitor 5 from an internal short, but also protects it from any occurrence, which might cause the passage of excessive current to flow through the flexible energized lead 3. As well known by those skilled in the art, an internal short within the capacitor 5 might cause rupture of the capacitor casing unless the excessive current therethrough is prevented by the blowing of the fusible device 9.

In this particular instance, it is desirable, upon blowing of the fuse device 9, to cause the bodily removal, or separation, of the end of the flexible energized conductor 3 away from the terminal 7 of the capacitor 5 to the position indicated by the dotted lines 10 of Fig. 1. This not only has the advantage of clearly indicating to a lineman the blowing of the fuse device 9 and the removal of the capacitor 5 from the circuit, but also prevents arc-over along the charred tube of the fusible device 9, which possibly might occur under certain conditions should no such separation be provided.

Figures 3-9 collectively illustrate the internal constructicn of the fusible device 9. As shown in Fig. 3, the fusible device 9 comprises a fuse mounting base 12, which, as shown more particularly in Figs. 7 and 8, is machined from hexagonal bronze stock. A slotted upstanding portion 13 is formed, and the base 12 is drilled as at 14, and tapped, to accommodate the terminal stud 7. Thus, the base 12 may be screwed directly on the terminal stud 7 of the capacitor 5 in the manner of a nut.

'I'he threads 14 constitute a securing means, associated with the conducting base 12, for detachably securing the conducting base 12 to a terminal 7 of the capacitor 5. i

The fuse link 16, as shown in Fig. 6, is of strap configuration having a locking bend 17 at one end thereof, the purpose for which will be more apparent hereinafter. Preferably, the fuse link or strap 16 has a hole 18 provided therein, as more clearly shown in Fig. 4 of the drawing. The hole 18, of course, insures that blowing of the fuse link 16 will occur at this point, because of the concentration of current flow through the remaining material adjacent this point.

One end 19 of the fuse strap 16 is inserted within the slot 20 of the upstanding portion 13 of the base 12, and

is secured thereto by any suitable means, in this particular case by brazing, as indicated in Fig. 5. The exposed end 21 of the energized lead 3 is secured to the fuse link 16 below the bend 17, as indicated in Fig. 5 of the drawing, by any suitable means, such as brazing. Preferably, the fuse strap 16 is formed of stainless steel, but it obviously mightbe formed of any suitable fusible material, which has the requisite mechanical strength.

a The fuse strap ,16, in being formed, has its ends sheared oif, so that upon the formation of the reverse or locking bend 17, the corners 22 thereof will bite into the inner surface of a fuse housing or fuse tube 23, which is forced thereon. In other words, following attachment of the fuse link 16 to the fuse base 12 and also to the exposed end 21 of the insulation covered lead 3, the fuse tube 23 may be forced over the fuse link 16 in the leftward direction, as viewed in Fig. 5 of the drawing. This operation is easy to perform since the locking bend 17 offers no restriction to movement of the fuse tube 23 in this direction.

However, when it is attempted to remove the fuse tube or housing 23 from the fusible device 9 by moving the same to the right, as in Fig. 5, the corners 22 of the sheared-off locking bend 17 will bite into the inner wall of the fuse tube 23, and prevent its removal therefrom.

The advantageous result following from this construction is that upon the passage of excessive current through the fuse device 9, as the result of any undesired condition occurring within the capacitor 5, or associated therewith, the fusion of the fuse link 16 adjacent the hole 18 thereof will cause the fuse tube 23 to remain with the end of the flexible lead 3, and to cover the exposed end thereof, so that a lineman may not touch the same and become shocked or otherwise seriously injured. The detachment of the fuse tube 23 from the base 12 is facilitated by the fact that preferably the fuse tube 23 is formed of any suitable gas-evolving material such as fiber, or the like, so that upon fusion of the fuse link 16, the resulting arc will evolve gases from the walls of the fuse tube 23, which gases will forceably expel the remaining portion 24- of the fuse link away from the base 12, as indicated in Fig. 2 of the drawings. It will be observed that the reverse locking bent 17 is provided at one end of the fuse links 16 past the position of securement of the exposed end 21 of the lead 3 to the fuse link 16, so that the locking bend 17 is not affected by the fusion of the fuse link 16, and thereby insures that the fuse housing or fuse tube 23 will remain attached to the fuse lead 3 in the manner as indicated in Figs. 1 and 2 of the drawing.

Fig. 9, which is a sectional end view of the fusible device 9, indicates how the reverse bend 17 does not prevent the expulsion of gases from the interior 25 of the fuse tube 23, there remaining at least three arcuately- .shaped openings 26 bypassing the locking bend 17 so that ready exhaust of the evolved gas is obtained.

Anadditional advantage of the particular configuration of the locking bend 17 of the fuse link 16 is that the gases, which are expelled from the interior 25 of the fuse tube 23, will be'apt to strike upon the hook-shaped bend 17 to insure a forcing of the fuse lead 3 and fuse tube 23 away from the mounting base 12 of the fuse device 9.

From the foregoing it will be apparent that our invention relates to an improved fusible device, which, for one particular application, is most suitable for secondary capacitor fuses. Such 230 volt secondary capacitors are individually supplied with fuses to prevent rupture of the case if capacitor short-circuits occur. When the fuse blows, it is desirable to physically remove the fuse from the circuit, so that the charred tube will not'arc-over, and also to provide an indication of the fuse operation. It is also necessary to keep the burned-off end of the fuse covered because it is energized, and hazardous if uncovered. Previous methods of securing the tube to the fuse were not positive in action and required additional small parts.

Our invention, in part, concerns a single part 16 which is shaped to serve both as a fusible element and also as a fuse-tube retainer. The bent part 17, which presses against the inside wall of the tube 23, secures the tube to the fuse element 16. After the tube 23 has been forced on the fuse assembly, it will not slide ofi, regardless of the rough handling the fuse may subsequently receive. Any attempt to pull the tube 23 off the fuse 9 merely tightens it. The inside of the insulating tube 23- is smooth, but the sharp corners 22 of the fuse element 16, which result from the shearing-off operation, dig into the inside of the tube 23. The bent portion 17 of the fuse element 16 does not carry current, and is not destroyed when the fuse operates. If the fuse blows, the tube 23 remains fixed to the lead 3 by the unburned portion 24 of the fuse element 16. Thus, our invention provides a very effective means of securing a fuse tube to the end of the fuse lead without the use of pins, clips or special machining operations.

Although we have shown and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein, by those skilled in the art, without departing from the spirit and scope of the invention.

We claim as our invention:

1. The combination in a fusible device for protecting electrical equipment of an insulating fuse tube, a conducting fuse link at least partially disposed Within said insulating fuse tube and having a reverse locking bend frictionally gripping the inner surface wall of said fuse tube to hold the fuse tube in position, and a detachable conducting lead for energizing the equipment attached to the fuse link so that upon blowing of the fuse link the fuse tube will remain secured to the detached lead to cover the end of the lead.

2. A fusible device including a conducting mounting base adaptable for securement to the terminal of a capacitor or like device for the protection of the same, a conducting lead for energizing the capacitor or like device, a conducting fuse link electrically interconnecting the mounting base with the lead, an insulating fuse tube enclosing the fuse link, and the fuse link having a locking bend adjacent one end thereof frictionally gripping the inner surface wall of said fuse tube to lock the insulating fuse tube in position.

3. A fusible device for the protection of a capacitor, or like device, said fusible device including a conducting mounting base, securing means associated with said conducting mounting base for detachably securing said conducting mounting base to the terminal of said capacitor, or like device, an energizing lead having a sheath of insulation thereabout with a short, bared end portion for energizing the capacitor, or like device, an insulating fuse tube over said bared end portion, a series conducting fuse link located wholly interiorly within said insulating fuse tube and having the end portions thereof electrically interconnecting the mounting base with said short, bared i end portion of the energizing lead, one end of said insulating fuse tube extending completely over the connection between the bared end portion of the insulated energizing lead and one end portion of the conducting fuse link, said one end of the insulating fuse tube also extending over the portion of the insulating sheath surrounding the energizing lead adjacent the bared end portion so that the energizing lead is wholly covered by insulation, means for attaching said insulating fuse tube to the energizing lead so that upon blowing of the fuse link the fuse tube and the energizing lead will become completely separated from the conducting mounting base so that a wide air gap exists therebetween, and the insulating fuse tube and the insulating sheath wholly covering the energizing lead so as to protect against hazardous contact with a bared energized portion of said energizing lead.

4-. The combination in a fuse device of a conducting fuse link having a reverse locking bend at one end thereof, a surrounding insulating fuse tube enclosing at least a portion of the fuse link, and the reverse locking bend of the fuse link actually making frictional contact with the inner wall of said insulating fuse tube to frictionally secure the same in place.

5. A fusible device for the protection of a capacitor, or like device, said fusible device including a conducting mounting base, securing means associated with said conducting mounting base for detachably securing said conducting mounting base to the terminal of said capacitor, or like device, an energizing lead having a sheath of insulation thereabout with a short, bared end portion for energizing the capacitor, or like device, an insulating fuse housing over said bared end portion, a series conducting fuse link located wholly interiorly within said insulating fuse housing and electrically connected between said mounting base and said short, bared end portion of the energizing lead, one end of said insulating fuse housing extending completely over the connection between the bared end portion of the insulated energizing lead and one end portion of the conducting fuse link, said one end of the insulating fuse housing also extending over the portion of the insulating sheath surrounding the energizing lead adjacent the bared end portion so that the energizing lead is wholly covered by insulation, means for attaching said insulating fuse housing to the energizing lead so that upon blowing of the fuse link the fuse housing and the energizing lead will become completely separated from the conducting mounting base so that a wide air gap exists therebetween, and the insulating fuse housing and the insulating sheath wholly covering the energizing lead so as to protect against hazardous contact with a bared energized portion of said energizing lead.

6. A fuse device including a round cylindrical fuse tube having a circular interior when viewed in cross-section, a strap-like conducting fuse link disposed longitudinally within said fuse tube, said strap-like conducting fuse link having a reverse locking bend at one end thereof, and the straight line interconnecting the corners of said reverse locking bend constituting a chord of the circular interior of the fuse tube.

7. A fusible device for the protection of a capacitor, or like device, said fusible device including an energizing lead having a sheath of insulation thereabout with a short, bared end portion for energizing the capacitor, or like device, an insulating fuse housing over said bared end portion, a series conducting fuse link located at least partially within said insulating fuse housing, means electrically connecting said fuse link between a terminal of the capacitor, or like device, and said short, bared end portion of the energizing lead, one end of said insulating fuse housing extending completely over the connection between the bared end portion of the insulated energizing lead and one end portion of the conducting fuse link, said one end of the insulating fuse housing also extending over the portion of the insulating sheath surrounding the energizing lead adjacent the bared end portion so that the energizing lead is wholly covered by insulation, means for attaching said insulating fuse housing to the energizing lead so that upon blowing of the fuse link the fuse housing and the energizing lead will become completely separated from said terminal of the capacitor, or like device, so that a wide air gap exists therebetween, and the insulating fuse housing and the insulating sheath Wholly covering the energizing lead so as to protect against hazardous contact with a bared energized portion of said energizing lead.

References Cited in the file of this patent UNITED STATES PATENTS 265,746 Brewtnall Oct. 10, 1882 1,147,448 Schweitzer July 20, 1915 1,315,162 Schneider Sept. 2, 1919 1,942,634 Bash Ian. 9, 1934 2,111,745 Boothe Mar. 22, 1938 2,115,592 Smith Apr. 26, 1938 2,193,203 Mosley Mar. 12, 1940 2,231,508 Schultz Feb. 11, 1941 2,231,599 Smith Feb. 11, 1941 2,276,703 Schmidt Mar. 17, 1942 2,281,074 Leonard Apr. 28, 1942 2,313,373 Sundt Mar. 9, 1943 2,337,872 Craig Dec. 28, 1943 2,423,197 Matson July 1, 1947 2,519,300 Wallace Aug. 15, 1950 2,645,690 Edsall et a1. July 14, 1953 FOREIGN PATENTS 91,751 Sweden Mar. 18, 1938 

